In light of the changing ethnic, racial and cultural demographics in U.S. schools, there is a growing need by scholars and practitioners for teaching practices that are informed by cultural knowledge possessed by students. This comes at a time when standardized testing of student achievement has been given a central role in efforts to improve K–12 education. This article begins with a discussion of ethnomathematics as a conceptual idea, and a practical way of rethinking ideology, content, and pedagogy in a rapidly changing climate of diversity. This is followed by a 5-year study on the Ethnomathematics and STEM Institute, which provides strategies for implementing professional development practices for educators. In Pacific as well as global communities, it is key to understand the role of experiential, values, and place-based learning. Through ethnomathematics, we endeavor to build capacity and networks across the Pacific by creating materials and strategies that are relevant, contextualized, and sustainable.